1. Field of the Invention
This invention relates to devices and methods used for cutting plugs of submerged substrate and, more particularly, a device and corresponding method used for cutting plugs of submerged aquatic vegetation (seagrass), a corresponding receptacle for transporting the cut plug, and a related method for transplanting a submerged aquatic vegetation plug.
2. Description of Related Art
The present invention provides an improved method and device for collecting, transporting, and transplanting plugs of submerged aquatic vegetation, in particular seagrass. More specifically, the present invention relates to a method and device for more easily and effectively collecting, transporting, and transplanting plugs of submerged aquatic vegetation. Further, the method and device can be utilized to more easily and effectively collect and transport a submerged substrate core sample. Further, the invention also provides for a transport receptacle to be utilized in conjunction with the device.
Submerged aquatic vegetation, seagrass in particular, is an essential part of the overall aquatic environment. Many species of marine animals rely on seagrasses for several functions including as a food source and as an area for cover and breeding. Whether it is for the purpose of restoring impacted seagrass beds or establishing new areas of seagrasses, the transplantation of seagrasses presents many physical and practical challenges to those who engage in this important activity.
Although different techniques of hand planting seagrasses have been historically employed by others, such as the peat pot method, staple method, and plug method (A Guide to Planting Seagrasses in the Gulf of Mexico, Fonseca), establishment of seagrass habitat using these methods has historically been problematic, particularly when transplanting relatively large areas of seagrass. In addition to varying degrees of success with these planting methods, these methods have also proven to be inefficient and physically demanding for those implementing them. More specifically, the peat pot method uses a typical 3-inch by 3-inch sod plugger to cut plugs of seagrass for transplanting. While relatively efficient, this method removes a limited amount of associated sediment with the cut seagrass plug, which makes it susceptible to failure when transplanted in recipient areas with high wave energy and/or current velocities. The staple method addresses some of the concerns about high wave energy/current velocity, but the method involves the time-consuming step of attaching the seagrass plants to staples before they are transplanted. Further, this method may result in the undesirable side effect of leaving potentially sharp pieces of partially-oxidized metal staples in the bottom of the recipient area. (Fonseca, p. 11). The plug method uses core tubes to remove plugs of seagrass with the associated sediment from donor beds and is generally recognized for achieving good results. (Fonseca, p. 9). In executing this method, a tube (typically 4 to 6-inch diameter PVC) is manually twisted into the substrate to the desired depth using a metal bar inserted through the top of the tube. The tube is then sealed with a plywood or PVC cap with a rubber stopper to create a vacuum to allow the plug to be removed from the submerged substrate with additional twisting and pulling of the metal bar inserted through the top of the tube. The plug is then planted directly from the core tube into a newly created hole at the recipient site by removing the rubber stopper allowing the plug to slide out of the tube.
Considering the inadequate results of these other methods to transplant seagrass plants and, in particular, relatively large areas of seagrasses in a reliable and economic fashion, the inventors devised the subject invention to improve the process and ultimately the success of transplanting seagrasses. More specifically, improvements upon the effective, but very time-consuming and physically demanding plug method as described above were addressed through this invention. The subject method and the related apparatus were developed after evaluating the various potential physical conditions of donor and recipient sites and implementing a procedure that recognized the growth habits, life histories, and the physical limitations of the species to be transplanted.
Similarly, the method and related apparatus can be utilized as a coring device to provide a more effective and efficient means for collecting a submerged substrate core sample for use in various geological and environmental endeavors.
U.S. Pat. No. 3,756,323 to Mays. (1971) and U.S. Pat. No. 5,492,181 to Grant (1994) each disclose devices to be used for cutting and planting plugs of turf or sod, which while addressing the cutting of substrate do not allow for the efficient cutting of a submerged unit, including the removal of a submerged aquatic vegetation unit without damaging the unit, nor do they describe any means for transporting the removed plug outside of the device. U.S. Pat. No. 4,282,684 to McLellan (1981) discloses a plant transplanter which provides for a device with cuts into the substrate to remove a plant for transplanting, but does not make any provisions for creating vacuum pressure in the cylindrical member to allow for efficient cutting and transplanting of submerged aquatic plants. Also, U.S. Pat. No. 4,135,752 to Long (1979) discloses a ground plugging device which combines a tubular metal body with teeth on the bottom edge and a blunt edge on top for accepting foot pressure; however, it does not address preserving the cut plug for purposes of transplanting nor does it address the problem of efficiently removing a plug of submerged substrate.
U.S. Pat. No. 6,070,537 to Anderson (2000) discloses a process and apparatus for planting shoots of nursery-incubated aquatic plants, but does not provide for the effective cutting and subsequent transplanting of existing viable seagrass plugs from a donor bed to a recipient site. In addition, U.S. Pat. No. 6,684,536 to Anderson (2004) discloses a planter for a slab of seagrass and related process, which provides a means for cutting a large quantity of seagrass for the purpose of transplanting; however, cutting of seagrasses in a slab, as opposed to smaller more manageable plugs as provided for in the subject invention, is often not a viable option based on the conditions at the donor bed or recipient site.